The invention relates to an implant. In particular, the invention relates to a bone implant like a bone nail.
An implant and particularly a bone implant includes a portion or section or end which is adapted to be first introduced into a body during implantation. In this specification, such a portion or section or end is referred to as leading portion or leading section or leading end. Consequently, an opposite portion or section or end of the implant is adapted to be introduced last, wherein this portion or section or end may additionally be configured for an engagement of a tool for inserting the implant into the body. Below, such a portion or section or end is referred to as trailing portion or trailing section or trailing end.
A bone implant may be a pin or a nail or screw. A bone nail may be an intramedullary nail, for example a femur nail, a humerus nail or a tibia nail. A bone screw may be a screw for fixing fragments of a bone fracture or may be a locking screw for locking a bone nail in the bone.
However, due to the anatomical variation of bones it may happen that the trailing end of a bone implant protrudes above the bone surface. The trailing end of the implant may act as an interface towards a target or aiming device. In order to create a solid fixation, nails may be provided with grooves in order to fit pegs on a post of a target device for accurate alignment, for sufficient fixation, and for controlling the forces applied during implant insertion and removal. It may occur that patients complain about pain after surgery in this area, especially when the implant trailing end is sticking out of the bone. This pain may be caused by sharp edges at the trailing end of the implant. Such edges may cause irritation and/or injury to the surrounding soft tissue.
U.S. Pat. No. 7,763,022 discloses a typical prior art intramedullary nail.
U.S. Pat. No. 6,443,954 B1 describes an intramedullary nail for securing portions of a bone together. A lag screw may extend through a radial bore in the nail. Furthermore, a cap screw may be screwed into the trailing end of the nail for holding the lag screw, wherein this lag screw has a spherical head portion.